United has become the first US airline to offer non-binary gender options throughout all booking channels in addition to providing the option to select the title “Mx.” during booking and in a MileagePlus customer profile. Customers now have the ability to identify themselves as M (male), F (female), U (undisclosed) or X (unspecified), corresponding with what is indicated on their passports or identification. Toby Enqvist, chief customer officer, said the airline is determined to lead the industry in LGBT inclusivity and is providing additional employee training to make the carrier even more welcoming for all customers and employees. United is working with the Human Rights Campaign and The Trevor Project on employee training initiatives, including teaching employees about preferred pronouns and the persistency of gender norms.